Medical crews around the Seattle area have a plan to continue transporting patients to the emergency room efficiently when traffic on Interstate 5 grinds to a crawl next week.

Starting Friday, several lanes of the Interstate-90 interchange will be shut down for 19 days, and many fear the stretch of I-5 from Tacoma to Seattle could become a parking lot, especially during rush hour.

For those 19 days, Airlift Northwest is adding a fifth helicopter to fly critical patients, who may be driven to the hospital under normal circumstances. The crew expects to be extremely busy, possibly even having to take off every half hour, which would add up to 50 percent more flights than a normal day.

"Those critical heart attacks, trauma from motor vehicle accidents - all of that is something we are hoping we can help with because the time in traffic will be significant," said Brenda Nelson, a flight nurse with Airlift Northwest.

On the ground, King County Medic One will station an extra unit to transport patients from south King County to Seattle.

"So it will be up roving in the Burien, North Highline, Tukwila, Renton areas," said Tom Gudmestad with King County Medic One.

For places further out like Auburn, Lake Tapps and Enumclaw, a chopper flight might be the only way to get patients to the care they need.

"We're anticipating the worst case scenario and I-5 provides our primary and critical transport route into hospitals in the city," Gudmestad said.

And within in the city limits, the Seattle fire department is scouting landing locations for Airlift flights. And the Airlift crew is gearing up for long hours in the air.

"We have approached it as a mass casualty incident command for 19 days," Nelson said.

For aid crews that still need to get to Seattle hospitals on the ground, Medic One has mapped out a list of alternate routes to keep units from getting stuck in a jam on I-5.